Advertising

Safety configuration for collisions

  • I have set up a program to stop the robot when it is hit. My problem is that I implement the checking of collisions in the Java program for one of the moves I am making and it works, the robot stops. When I tap the robot again it will continue on its motion.


    For other moves I am making I am not checking for collisions in the Java program. The reason for this is because I want to test the reaction of the underlying safety in the Kuka controller.


    I have in the SafetyConfiguration.sconf with a collision detection category, using a base related TCP-force component. I set the x- positive, x -negative, y- positive , y -negative, z- positive and z- negative each set to 50N.



    Now I don't really know how much force I am applying to the robot but when I hit it with increasing intensity I end up getting a message that the robot is not on its planned path but no safety message or e-stop.


    So I am worried that I don't have a good safety set up.


    I have the reaction set to stop 0.


    Maybe I should use Axis Torque monitoring instead. I did not get an E-stop using this when I tried it tough either.

  • The AMF "Collision detection" is essential. Use it and set the torque limits as low as your application allows for.



    Now I don't really know how much force I am applying to the robot but when I hit it with increasing intensity I end up getting a message that the robot is not on its planned path but no safety message or e-stop.


    That's how it works. When a PSM row is violated it will display which row was violated but only when it is violated. So if you push the robot with your hands then your TCP force component gets violated but as soon as you release the robot the row is no longer violated and the message disappears. If the robot crashes against a wall then the forces acting on the TCP will remain even after the brakes of the robot are closed, in that scenario the message may persist.


    It really makes it hard to troubleshoot if you have a complex configuration with many rows.



    I have in the SafetyConfiguration.sconf with a collision detection category, using a base related TCP-force component. I set the x- positive, x -negative, y- positive , y -negative, z- positive and z- negative each set to 50N


    Keep in mind that this particular AMF does not take torque into consideration.



    I have the reaction set to stop 0.


    This is why you see "Robot not on planned path". Stop0 shuts down the drives and immediately closes the brakes. Stop1 decelerates each drive as fast as it physically can the closes the brakes, since not all 7 axis can decelerate at the same rate the robot wont maintain the path. Stop1(path maintaining) is like Stop1 but it keeps the robot on the planned path.


    I recommend using Stop1 (path maintaining) for all collision AMF. From what I have observed Stop1 and Stop0 may cause unpredictable motions if you have a large tool attached to the end effector. This is because a small motion on a single axis may create a big motion on the tool. Ofcourse you have to make this might differ for every application so it is best to make this decision after you have made a risk assessment.

  • That makes a lot of sense.


    I added torque safety monitoring and just held the robot in place. Then I pushed against the robot and kept the pressure applied. The safety went red and then back off when I let released the robot.


    Thanks a lot for that, a I was running out of time I could spend on it.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account
Sign up for a new account in our community. It's easy!
Register a new account
Sign in
Already have an account? Sign in here.
Sign in Now